• Journal of Mechanical Science and Technology
• /
• 제20권5호
• /
• pp.658-667
• /
• 2006

Fractional derivative models, which are used to describe the viscoelastic behavior of material, have received considerable attention. Thus it is necessary to put forward the analysis solutions of dynamic systems containing a fractional derivative. Although previously reported such kind of fractional calculus-based constitutive models, it only handles the particularity of rational number in part, has great limitation by reason of only handling with particular rational number field. Simultaneously, the former study has great unreliability by reason of using the complementary error function which can't ensure uniform real number. In this paper, a new approach is proposed for an analytical scheme for dynamic system of a spring-mass-damper system of single-degree of freedom under general forcing conditions, whose damping is described by a fractional derivative of the order $0<{\alpha}<1$ which can be both irrational number and rational number. The new approach combines the fractional Green's function and Laplace transform of fractional derivative. Analytical examples of dynamic system under general forcing conditions obtained by means of this approach verify the feasibility very well with much higher reliability and universality.

• Archives of Pharmacal Research
• /
• 제10권1호
• /
• pp.1-8
• /
• 1987

One of the problems of derivatie spectrophotometry, the decrease of signal-to-noise ratio by derivative operations, was solved by three concepts of digital filtering, ensemble averaging, least squares polynomial smoothing and Fourier smoothing. The suthors made several compouter programs written in APPLE SOFT BASIC language for the actual applications of the concepts of these digital filters on UV spectrophotometer system. As a result, ensemble averaging could not be used as a routine operation for the spectrophotometer used. The maximum S/N ratio enhancement factors achieved by least squares polynomial smoothing were 6.17 and 7.47 for the spectra of Gaussian and Lorentzian distribution models, and by Fourier smoothing 16.42 and 11.78 for the spectra of two models, respectively.

• Journal of Biosystems Engineering
• /
• 제22권2호
• /
• pp.247-255
• /
• 1997

This study was conducted to develop regression models predicting sugar and acid contents in intact fruits nondestructively by using the second derivative of absorbance spectrum measured with a spectrophotometer wavelength range of 400nm to 2, 400nm. The correlation analysis was made in wavelength range of 600nm to 1, 100nm and 600nm to 2, 400nm respectively, in order to examine the feasibility of using a real time spectrophotometer, which covers the former range, in predicting sugar and acid contents. The second derivative data of the spectrum were obtained by varying smoothing size and derivative size of the original absorbance spectrum. SAS statistical package program was used for the regression analysis. The sugar contents of Fuji apple, Shingo pear md Yumyung peach could be predicted with SEPs of 0.40, 1.17 and 0.77 respectively, in the spectrum range of 600 to 1, 100nm. The highest correlation coefficient of the titratible acidity of apple was -0.45 at 2, 346nm and regression models indicated determination coefficient less than 0.47.

• Restorative Dentistry and Endodontics
• /
• 제38권4호
• /
• pp.194-203
• /
• 2013

Objectives: To investigate the effect of enamel matrix derivative (EMD) on periodontal healing of replanted teeth in animal models. Materials and Methods: The authors searched MEDLINE, PubMed, EMBASE, Cochrane Library, Web of Knowledge and Scopus for articles published up to Oct 2012. Animal studies in which EMD was applied in transplanted or replanted teeth with adequate controls and histological data were considered. Normal periodontal healing or root resorption determined by histology after EMD was applied in replanted teeth with adequate controls was used as outcome measures. The following search strategy was used: ('Emdogain' OR 'enamel matrix proteins' OR 'enamel matrix derivative') AND ('avulsion' OR 'transplantion' OR 'autotransplantation' OR 'replantation'). Results: Six animal studies were included in the final review. There was great heterogeneity in study design among included studies. Two studies with similar study designs were identified and analyzed by a meta-analysis. The pooled estimates showed a significantly higher normal healing and surface resorption and significantly less inflammatory and replacement resorption in EMD-treated groups compared with non-EMD-treated groups. Conclusions: With the limitations of this systematic review, the use of EMD led to greater normal periodontal healing and surface root resorption and less inflammatory and replacement root resorption in the presence of periodontal ligaments. However, no definite conclusion could be drawn with regard to the effect of EMD on periodontal healing and root resorption when no periodontal ligaments exist.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2006년도 정기 학술대회 논문집
• /
• pp.365-372
• /
• 2006

A new meshfree formulation is developed for material discontinuity problems. A local interfacial jump function which is defined as hyperplane function is embedded in the meshless approximation and the approximation accurately models functions with jumps in the displacement and the derivative fields. Diffuse derivative technique copes with difficulty due to complexity of derivative computation of meshfree approximation. Collocation method with diffuse derivative accelerates computing speed for numerical solution. By solving inclusion and composite material problems, the robustness and effectiveness of the method are verified.

• 대한한의학회지
• /
• 제23권2호
• /
• pp.39-56
• /
• 2002

Objective : The aim of this study is to investigate the inhibitory effect of lnjinchunggantang-derivative on acute and sub-acute hepatic fibrosis induced by $CCl_4$, and to compare the efficiency of lnjinchunggantang-derivative, Salviae Radix and Scirpi Tuber.Zeloariae Rhizoma on acute and sub-acute hepatic fibrosis induced by $CCl_4$. Method : Western blotting for collagen type N, quantitative RT-PCR and gross & histological findings on liver tissue (Hematoxylin & Eosin stain, Reticulin stain, Masson-Trichrome stain) were studied. Results : In the study on collagen type N expression, lnjinchunggantangcderivative, Scirpi Tuber.Zeloariae Rhizoma and Salviae Radix showed inhibitory effect in western blotting. In quantitative RT-PCR assay, lnjinchunggantang-derivative showed inhibitory effect on collagen type N expression in acute hepatic fibrosis model, whereas lnjinchunggantang-derivative, Scirpi Tuber.Zeloariae Rhizoma and Salviae Radix showed inhibitory effect on collagen type N expression in sub-acute hepatic fibrosis model. In the gross findings of acute and sub-acute hepatic fibrosis models,lnjinchunggantang-derivative, Salviae Radix and Scirpi Tuber. Zeloariae Rhizoma showed inhibitory effect on hepatic fibrosis in the order. In the histological findings of acute and sub-acute hepatic fibrosis models in Hematoxylin & Eosin, Reticulin and Masson-Trichrome staining, the liver of $CCl_4$-only group showed atrophy and necrotic change with white nodules whereas that of $CCl_4$+ Injinchunggantang-derivative showed no significant histological change with well preservation of the tone of the tissue, and Scirpi Tuber. Zeloariae Rhizoma and Salviae Radix group showed minimal fibrotic changes. In the scoring system of the extent of the inhibition of the hepatic fibrosis, lnjinchunggantang-derivative group showed statistically significant inhibitory effect(p<0.05) whereas Scirpi Tuber.Zeloariae Rhizoma and Salviae Radix group showed no statistically significant effect in the acute hepatic fibrosis model. In the sub-acute hepatic fibrosis model, lnjinchunggantang-derivative, Scirpi Tuber.Zeloariae Rhizoma and Salviae Radix group showed statistically significant effect (p<0.01). Conclusion : These results show that lnjinchunggantang-derivative, Salviae Radix and Scirpi Tuber.Zeloariae Rhizoma have inhibitory effect in the order on hepatic fibrosis induced by $CCl_4$ by suppressing the expression of collagen type N, ultimately preventing liver cirrhosis. To obtain more credible results in this experiment, developement of a new experimental model more similar to human hepatic fibrosis is still needed.

• Bulletin of the Korean Chemical Society
• /
• 제34권11호
• /
• pp.3391-3398
• /
• 2013

The carboxylated multiwall carbon nanotubes (MWCNT-COOH) and functionalized with isatin derivative (MWCNT-isatin) have been used as efficient adsorbents for the removal of lead (Pb) from aqueous solutions. The influence of variables including pH, concentration of the lead, amount of adsorbents and contact time was investigated by the batch method. The adsorption of the lead ions from aqueous solution by modified MWCNTs was studied kinetically using different kinetic models. The kinetic data were fitted with pseudo-first-order, pseudo-second-order, and intra-particle diffusion models. The sorption process with MWCNT-COOH and MWCNT-isatin was well described by pseudo-second-order and pseudo-first-order kinetics, respectively which it was agreed well with the experimental data. Also, it involved the particle-diffusion mechanism. The values of regression coefficient of various adsorption isotherm models like Langmuir, Freundlich and Tempkin to obtain the characteristic parameters of each model have been carried out. The Langmuir isotherm was found to best represent the measured sorption data for both adsorbent.

• Structural Engineering and Mechanics
• /
• 제41권1호
• /
• pp.113-137
• /
• 2012

Frame structures with viscoelastic (VE) dampers mounted on them are considered in this paper. It is the aim of this paper to compare the dynamic characteristics of frame structures with VE dampers when the dampers are modelled by means of different models. The classical rheological models, the model with the fractional order derivative, and the complex modulus model are used. A relatively large structure with VE dampers is considered in order to make the results of comparison more representative. The formulae for dissipation energy are derived. The finite element method is used to derive the equations of motion of the structure with dampers and such equations are written in terms of both physical and state-space variables. The solution to motion equations in the frequency domain is given and the dynamic properties of the structure with VE dampers are determined as a solution to the appropriately defined eigenvalue problem. Several conclusions concerning the applicability of a family of models of VE dampers are formulated on the basis of results of an extensive numerical analysis.

• International Journal of Aeronautical and Space Sciences
• /
• 제17권2호
• /
• pp.268-283
• /
• 2016

Aircraft manufacturing companies have to consider multiple derivatives to satisfy various market requirements. They modify or extend an existing aircraft to meet new market demands while keeping the development time and cost to a minimum. Many researchers have studied the derivative design process, but these research efforts consider baseline and derivative designs together, while using the whole set of design variables. Therefore, an efficient process that can reduce cost and time for aircraft derivative design is needed. In this research, a more efficient design process is proposed which obtains global changes from local changes in aircraft design in order to develop aircraft derivatives efficiently. Sensitivity analysis was introduced to remove unnecessary design variables that have a low impact on the objective function. This prevented wasting computational effort and time on low priority variables for design requirements and objectives. Additionally, uncertainty from the fidelity of analysis tools was considered in design optimization to increase the probability of optimization results. The Reliability Based Design Optimization (RBDO) and Possibility Based Design Optimization (PBDO) methods were proposed to handle the uncertainty in aircraft conceptual design optimization. In this paper, Collaborative Optimization (CO) based framework with RBDO and PBDO was implemented to consider uncertainty. The proposed method was applied for civil jet aircraft derivative design that increases cruise range and the number of passengers. The proposed process provided deterministic design optimization, RBDO, and PBDO results for given requirements.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2011년도 제37회 추계학술대회논문집
• /
• pp.985-987
• /
• 2011

본 논문은 파생형엔진의 설계를 위해 시동시간 예측모델을 개발하는 경우를 다루었다. 파생형엔진 설계를 위해 압축기/터빈의 특성맵을 새로 제안한 Modified Pump Scaling Law(MPS)방법을 사용하여 시동모델링에 필요한 아이들 이하 회전수(sub idle rpm) 영역으로 확장시켰고, 기준엔진의 손실특성에서 압력/온도와 엔진별 특성차이를 고려한 파생형엔진의 손실모델을 도출하였다. 이러한 특성을 반영한 파생형엔진의 시동시간 예측모델은 시험결과와 비교하여 비교적 양호한 결과를 나타내었다.